Heat exchangers



May 4, 1965 A. JOHNSTONE HEAT EXCHANGERS .2 Sheets-Sheet 1 Filed June 5, 1961 A. JOHNSTONE HEAT EXCHANGERS May 4, 1965 .2 Sheets-Sheet 2 Filed June 5, 1961 Mm Eh/4 Y United States Patent 3,181,602 HEAT EXCHANGERS Archibald Johnstone, Garforth, England, assignor, by mesne assignments, to Davidson & Company Limited, Beifast, Northern Ireland Filed June 5, 1961, Ser. No. 114,934 4 Claims. (Cl. 165--4) This invention relates to heat exchangers of the type in which relative rotation is provided between a segmental assembly of regenerative material and ducts at each end of the assembly for the respective passage in opposite directions through the segments of hot gas by which the segments are heated and gas that is in turn heated by the segments, some of the segments at any time receiving heat and others imparting heat. A notable use of heat exchangers of this type is in the heating of combustion air by the waste gases of boiler furnaces. In performing such a duty as this, the regenerative material must take a form that presents a large area for contact by the two gases in turn, and must have good thermal conductivity, to ensure a high rate of heat transfer and yet must not introduce undue pressure-drop between the two ends of the assembly. To satisfy these conditions, it is usual to form a mass of metal plates, shaped to form between each other lengthwise channels. The conditions to which the plates are subjected by the Waste gases of boiler or like furnaces result in time in corrosion of the plates. Renewal of the masses of plates in the segments from time to time can seriously interfere with the operation of an exchanger, particularly if access to the segments is only available in the axial direction of the exchanger, even in the case where the regenerative assembly is stationary and the ducts rotate with respect toit.

According to the present invention, a heat exchanger in which the ducts rotate with respect to a stationary segmental assembly of regenerative material has at the circumferential end of each segment an access opening fitted with a door, and movable blanking plates beyond both ends of the space within the segment occupied by the regenerative material to isolate that space from the ducts that are normally put into communication with the space during the operation of the heat exchanger.

With the blanking plates of a segment moved into space-isolating position, the door of that segment may be opened for removal and replacement of the regenerative material while the heat exchanger continues in operation, at only slight expense of efficiency in an exchanger having a large number of segments, say 24, because the opened segment is cut oil by the plates from the ducts that continue to move across the ends of the segment. The whole of the regenerative material of the exchanger may thus be replaced by single-segment stages with negligible interference with the working of the exchanger; or, if the opportunity arises to shut down the exchanger, several segments may be opened simultaneously to minimize the shutdown period.

When moved into isolating position, the plates should make a reasonable good gas-tight seal, to minimize loss of gas from the system or drawing of air into the system.

One form of blanking plate is a slide, of the same shape as the cross-section of a segment, introduced through a slot beyond the door opening. Each plate may be guided between runners along the division walls between segments, with the lower runners interrupted to allow the slide to push out any dust and dirt lodging between the runners. The slot may be sealed by a plate carried by the slide, and by a separate plate for application when the slid has been pulled clear of the exchanger casing for return of the segment to operation. Such slides may be located close to the ends of the mass of regenerative material.

3,181,662 Patented May 4, 1965 Another form of blanking plate consists of a damper hinged along a central radius of the segment and hearing at its edges against stop strips along the divisional walls when it is in isolating position. Again, two such hinged dampers may be mounted side-by-side, to bear on similar stops and on each other. Yet again, twosuch dampers may be hinged along the division walls, to bear either one on the other support or on a support bar when in isolating position. The bearing edges of the dampers and of the stops may be provided with asbestos strips to improve the sealing, e.g., strips folded round the edges and riveted in position.

The invention will now be further described with reference to the accompanying drawings in which FIGURE 1 is a diagrammatic vertical section through a heat exchanger with stationary regenerative mass and rotary sets of ducts;

FIGURE 2 is a diagrammatic plan view to a larger scale of a sliding blanking plate for use in the exchanger of FIGURE 1;

FIGURE 3 is a diagrammatic section showing two plates as in FIGURE 2;

FIGURE 4 is a fragmentary section taken on the line 4=i of FIGURE 2;

FIGURE 5 is a plan view of a number of segments;

FIGURE 6 corresponds to FIGURE 2, but shows a hinged blanking plate;

FIGURE 7 corresponds to FIGURE 2, but shows two plates as in FIGURE 6;

FIGURE 8 corresponds to FIGURE 6, but shows a pair of hinged blanking plates;

FIGURE 9 corresponds to FIGURE 7, but shows two pairs of plates as in FIGURE 8;

FIGURE 10 shows an alternative to FIGURE 9;

FIGURE 11 is an enlarged sectional detail of blanking plate edges and stop strips as in FIGURES 7 and 9; and

FIGURES 12 and 13 respectively show the bearing edges of the dampers of FIGURES 9 and 10.

As shown by FIGURES 1 and 5, the regenerative material 1 of the heat exchanger is contained in segmental compartments 2 formed between radial division plates 3, arcuate sections of a hub casing 6 and an outer casing 6A constituted mainly by doors 7 concentric with a central vertical shaft 8. The doors 7 are secured between stationary upper and lower casings 9, 10 having respectively a lateral inlet 11 for cold air and a lateral outlet 12 for heated air and co-axial inlet and outlets 13, 14 for outgoing and incoming waste gas. Sliding blanking plates 15, as in FIGURE 2 are inserted through slots 16 in the outer casing 6A (FIGURE 4) above and below the door opening. The casings 9, 10 contain similar but mutually inverted double rotatable duct units A, B each of which is connected to the appropriate outlet 14, or inlet 13 by a short circular section 17 and a seal 18. The duct unit A is driven by a gear (not shown) meshing with a gear ring 19 and in turn drives unit B through the shaft 8.

The metal plates 1 are formed into several packs, which together till a segment 2, inserted through and enclosed by the doors 7. They can be removed and replaced whilst the exchanger is in operation by the use of blanking plates above and below a door of a segment so as to cut oil the air or gas flow from that segment. In FIGURES 2 and 3 a blanking plate 15 in the form of a slide corresponding in shape to a segment 2 to give a close fit, is provided with pairs of guides 2d Welded to its underside to fit round a support rail 21 welded at its ends to the hub casing 6 and the outer casing 6A. The plate also slides along upper and lower runners 22, 23 welded along the division Walls 3 of the segments. This sliding constructionenables the blanking plates to be located only a short distance above and below the regenerative material 1;

The lower runners 23 are provided with slots 25 to allow dust and dirt which has accumulatedduring operseparate plates are bolted to the brackets 27 to seal the slot 16. V

FIGURES 6 and 7 show a second form of blanking plate comprising a damper 29 of segmental shape adapted to rotate onspindles 30 fixed on the hub casing 6 and outer casing 6A, from a fully open position (as shown) allowing almostcompletely unrestricted gas flow, to a fully closed position, its rotation being arrested by stop strips 31 welded to each side of the division plates 3. Similarly two narrower segmental dampers 32 may be mounted side by side to rotate on spindles 33 as shown in FIGURES 8 and 9 and'to bear on stop strips 34 on the division plates and on each other (FIGURES 11 and 12) when in closed position.

Again two such dampers 35 (FIGURE 10) may be hinged along the division plates. 3 to lie along the plates when in open position and to bear on a support bar 36 when in closed position (FIGURE 13).

The bearing edges of the dampers 29, 32, 35 and the stops 31, '34 are provided with asbestos strips 37 (FIG- URES 11, 12, and 13) to afford adequate sealing, the strips beingsecured by'rivets 38.

The width of the door opening (seen at 28 m FIG- URE 4) is preferably almost the fullwidth of each segment at the outer casing 6A to allow the regenerative material to be inserted asla'rge. packs. Thus, with the sides of the door opening." stayed from the division walls by parallel stays 39 ,(FIGURE'S'), the outermost pack can be parallel-sided to fit the full widthb'etween the stays, and the inner packs can be of' diminishing width, with tapering sides, to fit between the converging walls to the innermost part of the segment. If necessary, to

keep individual packs to'aw'eight permitting. or ready,

handling, one pack may be super-imposedon' another to build up the axial dimension of the mass.

The door' 7 (FIGURE 4) for each segment may be hinged alongside the door opening, with hinged and sliding wedging plates at the free side to be driven into wedging sockets projecting at the side of "the door opening and with hinge pins that alsocan be driven at the hinge sides of the doors, tobring' the inner faces of the doors into tight sealing position all round the door openings, with asbestos gaskets to complete the seals. Alternatively, lift-out doors may be used, with locking bars'to be screwed up or driven to eifect sealing.

What I claim is: I

1. A regenerative heat exchanger comprising a stationary cylindrical casing divided into segments, regen erative material in the said segments, a plurality of ducts at each end of the casing and rotatable with respect to the segments, an access opening to each segment in the periphery of the casing, a door to each said opening, and movable blanking-off plates for closing the ends of a selected segment, each said 'plate including means extending to and operable from the exterior of said casing for shifting its position to isolate that segment from the rotatable ducts before the door to that segment is moved to provide access to the segment.

2. A regenerative heat exchanger comprising a stationary casing divided into segments, regenerative material in the said segments, a plurality of ducts at each end of the casing and rotatable with respect tothe segments, an access opening to each segment in the periphery of the casing, a door to each said opening, slots in the periphery of thecasing atiboth endsof each segment and outside of the area of said access openings, and slidable blanking-oh? plates inserta'ble through the slots of'a selected segment, each said plate including means extending to and operable from the exterior of said casing for shifting its positionto isolate that segment from the rotatable ducts before the door to that segment is moved to provide access to the segment.

3. A heat-exchanger as in claim 2, comprising guiding and sealing runnerswithin each segment for engagement by the slidable blanking-off plates.

4. A regenerative heatexchanger comprising a stationary casing divided-into segments, regenerative mater al inthe said segments, a plurality of ducts at each end of the casing and rotatable with respect to the segments, an access opening to each segment in the periphery of the casing, a door to each said opening, slots in the'periphery of the casing at both ends of each segment and outside of the area or" said access openings, removable plates sealing the said slots, and 'slidable blanking-off plates insertable through the slots of aselec'ted segment, after removal of the said slot sealing plates, to-isolate that segment from the rotatable ducts before the door to that segment is moved to-provid'e accessrto the segment, each blanking-0E plate having attached thereto a'plate for seal ing. a slot throughwhich the blanking-oif'plate is inserted.

V Rei'erenees Cited ibyth Examiner UNITED STATES PATENTS 1,688,700 10/28 Gauss 4 1,820,199 8/31 Riley 1654 1,859,573 5/32 Riley 1654 1,985,268 12/34 Yerrick 1654 1,985,269 12/34 Yerrick 1654 2,337,907 12/43 Lundstrom, 165-7 2,549,583 4/51 Eckersley 1655 2,873,952 2/59 Mudersbach et al 1659 2,883,160 4/59. Palmiter' et al .165-7 2,938,712 5/60 Pellmyr- 165-137 FOREIGN PATENTS 592,483 5/25 France.

CHARLES ,SUKALO, Primary E am ner, 

1. A REGENERATIVE HEAT EXCHANGER COMPRISING A STATIONARY CYLINDRICAL CASING DIVIDED INTO SEGMENTS, REGENERATIVE MATERIAL IN THE SAID SEGMENTS, A PLURALITY OF DUCTS AT EACH END OF THE CASING AND ROTATABLE WITH RESPECT TO THE SEGMENTS, AN ACCESS OPENING TO EACH SEGMENT IN THE PERIPHERY OF THE CASING, A DOOR TO EACH SAID OPENING, AND MOVABLE BLANKING-OFF PLATES FOR CLOSING THE ENDS OF A SELECTED SEGMENT, EACH SAID PLATE INCLUDING MEANS EXTENDING TO AND OPERABLE FROM THE EXTERIOF OF SAID CASING FOR SHIFTING ITS POSITION TO ISOLATE THAT SEGMENT FROM THE ROTATABLE DUCTS DEFORE THE DOOR TO THAT SEGMENT IS MOVED TO PROVIDE ACCESS TO THE SEGMENT. 